Seismic performance of three dynamically similar buildings with different vertical irregularities

Abstract

Abstract Earthquake forces are the most Dynamic in nature and should be resisted by the building structure. The irregular configuration in the structure, either in elevation or plan, is one of the major reasons for a structure’s collapse. From previous earthquakes, it was discovered that a building’s performance in seismic excitations is primarily dependent on its configuration. In reality, the concept of “perfect regularity” does not exist, as real building structures contain irregularity needed by aesthetic, and functional needs and demands. In this paper, three reinforced concrete (RCC) building structures comprising eight storeys have been modelled with varying vertical irregularities but nearly equal fundamental time periods. Building 1 has no irregularity yet building 2 and building 3 comprises of different vertical irregularities. The aim is to compare the seismic behaviour in the form of key seismic performance parameters such as maximum acceleration, maximum displacement, and base shear. It was found that the fundamental time period of the models remains almost similar while the seismic performance of the three buildings varies considerably. When the models are analysed for nonlinear dynamic analysis (Fast Nonlinear Analysis) the key parameters show the variations due to different mass and stiffness distributions comprising vertical irregularity. It was also noted that the characteristics of the earthquake are controlling the key seismic parameters.